/**
 * Created with IntelliJ IDEA.
 * Description:
 * User:DELL
 * Date:2025-04-03
 * Time:15:12
 */
public class Test1 {
    public String convert(String s, int numRows) {
        //处理边界
        if(numRows==1){
            return s;
        }
        int d=2*numRows-2,n=s.length();
        StringBuilder ret=new StringBuilder();
        //处理第一行
        for(int i=0;i<n;i+=d){
            ret.append(s.charAt(i));
        }
        //处理中间行
        for(int k=1;k<numRows-1;k++){
            for(int i=k,j=d-i;i<n||j<n;i+=d,j+=d){
                if(i<n){
                    ret.append(s.charAt(i));
                }
                if(j<n){
                    ret.append(s.charAt(j));
                }
            }
        }
        //处理最后一行、
        for(int i=numRows-1;i<n;i+=d){
            ret.append(s.charAt(i));
        }
        return ret.toString();
    }
}
